There have been many approaches suggested for preparing shelving systems, particularly for industrial purposes. Such shelving systems have generally attempted to produce shelving that is easily adjustable or able to be knocked down with relative ease while at the same time providing sufficient support to accept relatively heavy loads, especially those that industrial shelving can often be subjected to. However, many of these systems have not achieved these desired goals.
An early example of a shelf mounting structure is shown in Doherty, U.S. Pat. No. 3,245,365. This structure was comprised of a solid, cylindrical sleeve provided midway along each side of the shelf that would fit over a support post. Each sleeve included a longitudinally extending groove or notch formed in the interior side wall for receiving a spring type locking member that would be insertable in that groove so that a toothed edge provided on the bottom end of the spring member would extend below the sleeve member and engage the post. In that position, when the sleeve was placed over the locking member, or vice versa, and load applied to the shelf, would force the toothed edge toward the pole thereby locking the shelf in the desired position.
Thereafter, the art seemed to develop about the concept of using two engaging wedge shaped or frusto conical surfaces and the use of an insert member that would fit against or over the post and provide one of those wedge or frusto-conical surfaces. In the frusto conical systems, the insert was provided with a cylindrically shaped interior opening that would ride along the post and a frusto conical exterior surface. A separate support structure mounted on, within or to the shelf structure was provided with a complementary frusto conically shaped internal bore so that when the support structure was placed over the insert and the two frusto conical sections were joined, the pair would mate along their entire length with those mating surfaces providing the support for the shelf. Exemplary of this frusto conical approach are U.S. Pat. Nos. 3,424,111, 3,675,598, 3,757,705, 3,874,511, 4,318,352, and 4,444,125.
In U.S. Pat. No. 3,424,111, Maslow, a two-piece frusto conical insert member also included an exterior groove for receiving an O-ring for holding the insert member comprised of two halves that would fit together and in place about the post. The insert member also included a radially inwardly directed rib on the inner surface for mating with one of the grooves provided on the post. Support for the shelf was provided by the mating of the two frusto conical surfaces, one on the exterior of the insert, the other in the form of a frusto conical bore within a support member fixed to the shelf. After being loaded, separation of the support system elements would sometimes prove difficult because of the total surface engagement and the wedging action between those two frusto conical surfaces. It should be noted that the two piece insert construction had a tendency when struck, as when moving the shelving, to actually pop apart or separate and fall off the post causing assembly or shelf movement problems.
Rather than using the internally directed rib, the U.S. Pat. No. 3,675,598 approach was to hold the insert member in place with a set screw, positioned in a collar at the lower end of the insert.
In U.S. Pat. No. 3,757,705, a C-clip was placed about the two halves of the insert but this occurred following placement of the frusto conically shaped sleeve type corner support thereover. The C-clip would retain the corner support in position on the insert member and on the post. The corner support was a split sleeve structure so as to provide some elastic lateral expansion with the C-shaped ring, provided at the top of the two halved insert able to resist inadvertent uplifting of the shelf.
In U.S. Pat. No. 3,874,511, the two piece frusto conical insert is again used. The shelf has a frusto conically shaped opening at each corner, and the insert member included an annular lip at its base which assisted in limiting downward movement of the corner member. Primary support for the shelf, however, continued to be provided by the pair of mating frusto conical surfaces.
Tashman, U.S. Pat. No. 4,138,953, also uses the mating frusto conical surface approach, but rather than using a two piece insert member, Tashman provides a one piece, split ring tapered member that also incorporates the interior rib for positioning that insert member on the post.
In Maslow, U.S. Pat. No. 3,604,369, the thought behind the support technqiue was again directed at a wedge concept. Rather than employing mating frusto conical surfaces, a simple wedge member, provided with a plurality of inwardly directed curved bosses, graduated so as to mate with similar female bosses in the post, would be placed on the post. A sleeve member, provided with a tapered or angled slot in the form of a key way for receiving the tapered wedge, would then be slid down the post and over the wedge with the wedge serving to hold the sleeve in position on the post.
French Pat. No. 855,715, employs a sleeve that is also positioned at the center point of the side of a shelf, and is provided along most of its interior with a cylindrical surface. The bottom portion tapers outwardly away from the post in the form of a frusto conical portion. A rubber O-ring is positioned on the post, although not positively as it can move along the post even prior to being deformed. The O-ring is received in this frusto conical portion in the lower half of the sleeve. As load is placed on the shelf, however, the O-ring will be compressed or deformed in between the sleeve and the post under load conditions so that it does not provide a positive stop structure.
Chung et al, U.S. Pat. No. 4,128,064, employs two threadedly mating sections, the innermost having an inwardly directed rib to again mate with a groove provided in the post with the threaded sections serving to clamp the shelf therebetween.
Finally, Kelson, U.S. Pat. No. 3,344,756, shows the use of set screws to hold a corner support member on a post and Hendricks, U.S. Pat. No. 2,388,056; Ingwer, U.S. Pat. No. 2,705,119, and Snurr, U.S. Pat. No. 3,741,514, show the use of hardened ball bearings in various approaches to both support and allow for adjustability in a support structure.